System of communication by means of current impulses



July 11, 1933. E. KRUHME ET AL SYSTEM OF COMMUNICATION BY MEANS OF CURRENT IMPULSES Filed Feb. 19, 951

5 Sheets-Sheet l KRUHME 53- AL L fl SYSTEM 5)? CONEZUHEQKTION BY MEANS OF CURRENT IMPULSES Filed Feb. 19, 1951 5 Sheets-Sheet 2 Edy 1933. E, KRUHME ET AL 1,918,043

SYSTEM OF COMMUNICATION BY MEANS OF CURRENT IMPULSES Filed Feb. 19, 1931 5 Sheets-Sheet 3 5- .0 5 Fig.6

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July 11, 1933. E. KRUHME El AL 1,918,043

SYSTEM OF COMMUNICATION BY MEANS OF CURRENT IMPULSES Filed Feb. 19, 1931 5 Sheets-Sheet 4 July 11, 1933. KRUHME ET AL 1,918,043

SYSTEM OF COMMUNICATION BY MEANS OF CURRENT IMPULSES Filed Feb. 19, 1931 5 Sheets-Sheet 5 Jr; 1 071151: ,f'picfi Krwiz fizgyust Jab; Jhrfiar l 2 055 berg w x W florneyg Patented July 11, 1933 r FFICE ERICK KRUHIVIE, OF BERLIN-TBEPTOW, AUGUST J IP1 AIIZ) EHRHARD ROSSBERG, 01'! BE EN-SIEIJEENSSTADT, GERMANY, ASSIGNGRS TO & HALSKE JAKT'IEIBL GESELLSCHAFT, OE SIEllEENSSTAEJT NEAR BER'LKN, GERIVlANY, A CORPORATION .025

GER-MANY SYSTEM. OF COMMUNICATIQN' BY MEANS OF OUR-RENT IMPULSES Application filed February 19, 1931, Serial No. 516,908, and in Germany February '7, 1930.

Our invention relates to electric telegraph systems, and particularly to such .as-employ printing telegraphs.

The main purpose of this invention is to provide, at one or more points of the transmission system, distortion-correcting devices (regenerative repeaters) by which the signals received are transmitted or carried on in a form free from distortion. It is also an object of the invention to provide means for the transmission of currents other than telegraphic currents, without any detrimental act-ion on said repeatersmnd without said repeaters impairing the transmission of such other currents.

In the transmission of curre .timpulses the shape (it the curve, in particular the lengta of the individual current impulses, is changed (distorted) along the path from thetransmitter to the receiverhy various causes, primarily the electric properties of the means of transmission. It the distortion becomes so strong'that a reliablereception of the current impulses at the receiving end is no longer possible. it is necessary to employ a suitable correcting or anti-distortion device for eliminating. either completely or substantially so. the distortion of the current impulses which has occurred.

For correcting the telegraph signals, there have been employed hitherto relay transmitters or repeaters which iutheir operation differ from each other as to the. timing of the opening and closing of their contacts, and which are interposed at a suitable point in the path of transmission. It it is desired to use only a relatively small number or paratus. the degree of correction obtainable is limited and in many cases inadequate for practical use. Moreover, there a1 the danthat a certain error will occur at each ransmission and that such errors will he .dded to one another when the transmission is ma: e through several successive repeaters.

For this reason, certain types of telegraph systems make use of rotary repeaters which in theirniode of operation must he adapted to the particular time of the tel ph system employed. In 1 Ll-ll tclec ph plants which operate with telcrraph signals comsuch ap- V posed of groups of current impulses, and require accurate synchronism of the transmitting and receiving distributors for the correct transmission of the signals, rotary repeaters have been employed, which consist substantiall of a receiving distributor coupled rigidly with a transmitting distributor of the type employed in high-speed telegraphy. The individual current impulses reaching the receiving distributor are passed through the individual distributor segments to impulse storing or holding devices which in their turn connect the voltages correspond ing with the individual current impulses to the segments of the transmittingdistributor. For the correct operation of the this repeatin apparatus it is necessary to secure accurate synchronism of the distributors. with the other transmitting and receiving distributors of the high-speed. telegraph line employed.

In high-speed telegraphy, the :groups of current impulses follow one another in continuous sequence at constant intervals. In telegraph systems operatingon thestartetop principle and in similar systems, the groups of current impulses succeed one another at intervals of varying length, and in connection with such systems there are employed distortion-correcting repeaters which, in

stead of rotating continuously, are started either in response to the first current impulse or by a special starting impulse at'the'beginning oi each group of current impulses. In this case the distributors of the distortioncorrectin repeater require only a relatively small degree of accuracy as to their syncronism with the distributors of the telegraph apparatus, in accordance with the ralatively low degree of synchronism accuracy customary in such apparatus. In this case also, there is employed in conjunction with such repeaters, a receiving distributor which .receives the arriving current impulses of each group and transmits them individually ito" the storing devices which effect the distortionless further transmission;there is also used. if desired, a transmitting distributor. which passes the stored impulses on to the next section of the line.

of rest. It is then, of course The application of the described transmission apparatus leads to certain troubles in the case of plants in which in addition to the normal telegraph si nals special current impulses are to be transmitted, which in their properties are different from the telegraph signals proper. This is the case in telerecording plants with selector operation, as in these plants in addition to the signals employed for the telerecording traflic the selector impulses serving for the setting of the connecting apparatus as well as, in some cases further impulses, such as signal impulses, have to be transmitted. The di'lliculty arising in such cases consists in the fact that the correcting repeating apparatus which must be connected at a suitable point in the connecting line, does not permit of a correct transmission of the impulses which dilfer from the telegraph signals.

These difficulties may according to our invention be eliminated by providing switcl1- gear for by-passing or disconnecting the correcting current impulse repeaters which permit the transmission of th currents difi'ering from the telegraph impulses. The disconnection of the current impulse repeaters will be advisable particularly then when the telegraph impulses as well as the impulses different from them are direct current impulses while in the event of partial or exclusive use of alternating current for the impulses a bypassing of the current impulse repeaters by the use of filters well known in the art may be preferable.

The mode of operating the current impulse repeaters may, in particular, be such that they are able to transmit only during the telegraph tratlic, by being, for example, connected in circuit at the commencement of the traflic and disconnected when th trafiic is finished. The process of connecting or dis connecting the apparatus provided for bypassing the current impulse repeaters is to be considered equivalent with the process of connecting or disconnecting the current impulse repeater itself. For plants in which exchange equipment is employed, more particularly in plants with selector or dial operation, a simple solution results from the fact that the effect of the current impulse repeater or the by-pass equipment depends upon switching means which become operative when the connection is made or broken. In telerecording plants with dial operation the control of the current impulse repeaters or their by-pass devices may take place by giving, after the desired subscriber has been reached a disengaged signal which differs from the disengaged signals of the individual selector steps. This special disengaged signal may then control in the repeater apparatus, a relay which eliminates the by-pass or" the correcting repeater existing in the state easily possible to use special repeater apparatus for repeating the impulses which are different from the telegraph impulses proper, and which, if desired, may work without correction.

Further details of our invention will be understood from the following specification and the drawings affixed to it. The embodiment of our invention illustrated by way of example is based upon the assumption that telerecordin plant working on the start stop principle are employed in which the signal composed of live current impulses is initiated by a start impulse and, as a rule, finished by a stop impulse.

Tn the drawings:

Fig. 1 is a diagrammatic View showing the arrangement and wiring for a correcting repeating system such as maybe used in connection with our invention while the remaining figures illustrate the connection of such a repeater apparatus in the system of an automatic exchange for telerecording subscriber stations,

Fig. 2 is a diagram of a complete telerecording system, while Figs. 3 to 6 illustrate details of the wiring diagram, and

Fig. 7 the wiring diagram of the plant into which they are to be combined.

Referring to Fig. l of the drawings, the repeater system consists substantially of the receiving relay ER- connected in the incoming line L which relay in alternating current operation is designed as a polarized relay, the receiving distributor V the impulse storing relays R to R and the transmitting distributor V connected in the outgoing line L Each of the two distributors possesses a segment ring S or S respectively made with six sections 10 to 15 or 20 to 25 respectively and a solid ring which is successively connected to the individual sections of the segment ring when the wiper B or B respectively rotates. The wipers are held in the inoperative position by locking levers H and H respectively. The release takes place when the release magnets AM or AM are energized.

With the wiper B is rigidly connected a cam C which controls a switch contact AK. This contact is connected in the circuit of the release magnet AM of the transmitter distributor V and effects its release after the receiver distributor V has started. The relative timing of the two rotations depends upon the angular position of the cam C. Simultaneously with the release magnet AM there is energized a release and holding relay AHE- which causes the retransmission of the start impulse into the outgoing line L The system illustrated functions in the following manner, upon the reception, over the line L of a telegraph signal consisting of a release current impulse and the five signal current impulses as well as, in some cases,

neiaoee a holding current impulse: The release cur rent impulse by energizing the receiving relay ER first changes the connection of the armature of the relay from the positive pole on to the negative pole of the local battery OB. The following circuit for the release magnet of the receiving distributor is then completed: negative pole oi the battery B, armature of the receiving relay Ell, solid contact ring of the receiving distributor V wiper B Zero segment of the segment ring S release magnet Al /l positive pole of the battery OB. The locking lever H is released and sets the wiper tree to perform one revolution. The wiper then sweeps across the individual segments 11 to 15 of the segment rin S hich are connected to V the storing relays R to R As the speed of rotation of the wipers is adapted to the telegraphing speed, the storing relays R to R are successively energized when the wiper sweeps across the segments 11 to 15, in correspondence with the individual current impulses. If, for example, the first signal current impulse is opposed to the release current impulse, the following cir:

cuit is completed at the moment when the wiper 13, makes contact with the segment 11: ground, half of the battery (EB (positivepole), armature of the relay (meanwhile. turned back into the position illustwu ed), wiper B contact segment ll, stor: relay R ground. The armature-of the sterins relay R for instance, is thereby brou 'ht It thus the distributor brush l into the position illustrated. The adjustment of the remaining storing. relays R to is etlected in a similar manner.

Partly positive and partly negative potential is now applied to the signal current segments of the segment ring of the transmitting distributor, according to the composition of the telegraph signal and the corresponding adjustment of the storing relays. E is released. the 'oin r line L is through the solid contactring of V successively connected with +-and respectively through the individual segment sections 2i to The release takes place as soon as the cam U connected with the wiper B of the receiving distributor closes the release contact AK. The release magnet AM: thus energized which relea c the wiper B; by operating" the loci-ring lever H and simultaneously the hold ng relay AER is made to respond, which turns it." :11 temporarily from the position of restworking position. In this working position the negative pole of the battery isconuc ted to the outgoing line L: thereby e'fiiectinc' the transmission of the release impulse across he circuit: ground, half of the battery 03 (r ative pole) armature of the rela r segment 20, wiper B line L Yi -Jen the wiper B: has left the zero segment, the release contact AK is again opened, so that the locking hiverll as'well as the armature of the relay Al'llt return into the inoperative position. By the armature of AER the positive pole oi (,B is connected to the zero mag net 20., so that after the. revolution is finished the wiper l on running on to the zero segmeutsends a clcaringimpulse into the line L The repeater equipment illustrated in Fi 1 must be understood instead of it we may use any other customary or approved arrangement.

By using;- known connections the repeater :stem may be so designed that a duplex op- Farr Cons of trallic is possible over the telegraph mes.

An embodiment of our invention employing the above described repeating equipment s illustrated in Fig. 2 of the drawings. This shows diagrammatically the conneclieu of two subscribers TS and T S which can be connected by one or a plurality of cent al ojilces or err'changcs, for instance the two oiiices A and B. The connection may partly take place across toll lines, for instance L and L One central. oliice A may simultaneously subdivide the toll line in a suitable manner. The connection, for instance, from the subscriber TS to the subscriber 'll'ff i, takes place in. well known manner by operating select s W 3 VVSQ, VVS. in a plurality out selector steps. The selectors WS and VJS may, for instance, be accommodated in the central o'ltice A, further selectors W'ti in the oilice In the central office A there is turthernurre housed correcting repeater EU which. corrects the telegraph impulses, but in the posi .n of rest or up to tile complete through-connection is bridged over by a bypassY .r disconnected altogether. The startingof the repeater talres place only when the telegraph impulses are transmitted or when the through connection has been completed.

to 6, which are partial views related to one another as indicated in Fig. 7, show a diagrrzun of? connections of the subscribers apparatus and switching arrangements necessary for setting-up a connection, only the.

the two pairs of wires being provided for the trafiic one of the two directions. It will be understood, however, that 1t is also possible to employ other systems of transmission.

an example only, and

ration or alternative oper-ationin both direcmore particularly such for which only twowire connecting lines are required.

At the central station the impulses dispatched by the subscriber TS are received by a receiving relay ER, while the dispatch of impulses to the subscriber takes place by a transmitting relay ES.

Every circuit to be set up passes within the central office first over a )l'0-S0l8Ct-2I1 VVV which in a well-known manner selects a line leading to an idle group selector or final switch respectively. The busy test is made by means of a testing relay T which is connected to a pilot wire 0 combined with one of the two main trailic lines a, b. There is also apportioned to each subscriber an answering or back ring device AN which will be more fully discussed later on.

From the preselector Vl V the connecting lines lead to the final switch or connector LlV, which together with the switching arrangements pertaining thereto is illustrated in Fig. 4. Tn front of the final switch there is, however, connected a repeating device serving for the correction of the signals, and which is shown in Fig. 5 ol the drawings. This repeater device consists of two substantially similar correcting repeaters, which are provided for the two directions of trafiic, each consisting of a receiving distributor, a transmitting distributor and a group of storing relays.

From the final switch LVV shown in Fig. 4 the connecting lines are extended to the pro-selector connection VlV (see Fig. 6) of the called subscriber. The connection may be made through a sub-station ZA in which further selectors are located. This station may, however, be part of the central station. lVith the presele'ctor VlV is connected an auton'iatic answering or back ring device AN which when the through connection is completed transmits a signal from the called party, more particularly his name and, if desired, the address, asa check for the caling party that the correct connection has been completed. The diagram of connections of the called party TS is shown on the right-hand side of Fig. 6. he diagram of connections according to Fig. 6 is otherwise identical with the diagram of connections illustrated in Fig. 3 for the calling party TS.

In describing the mode of operation of the system it is in the following assumed that the subscribed T S wishes to communicate with the subscriber TS.

For the purpose of calling up the central oilice the transmitting contacts (Fig. are first turned from the position of rest shown (false position of rest) into the service position of rest, so that the direction of the current in the receiving relay ER of the central oilice is reversed. The switching on of the potential divider ST may have taken place previously by a special manipulation.

The reversal of the direction of the current in the relay ER of the central oliice causes the changing-over of the contact 02* whereby the following circuit for the relay X is completed: positive pole of the source of current, UA SS X, 6 1, SS UA negative pole. UA and UA are overload circuit breakers which like the fuses SS and SS serve to protect the sources of current as well as the apparatus.

By the response of the relay X the pre-selector VlW is marked and simultaneously engaged, an auxiliary relay R first being connected in circuit by the contact an in the following circuit: positive pole, m R, fuse SS3, overload circuit breaker UA negative pole. The contact :0 prepares the connection through the ring wire. The relay R closes with its contact 13 an exciter circuit for the rotary magnet DV ot the pre-selcctor VlV, so that it starts in the circuit: positive pole, wiper ml of the pre-selector, t 1' 11, DV, SS RU, UA negative pole. By the interrupting contact RU, which may, for instance. be a relay interrupter, the selector turned until the final switch 120 of the pre selector has found the negative pole of an idle final switch LEV (Fig. i) and the pilot relay T is made to respond thereby in the circuit: positive pole, testing relay T, '00, c- 9 wire to .the final switch (Fig. 4), C, c 7: UA negative pole. The testing relay T (Fig. 3) now disconnects the highohmic winding (2), so that through the circuit 1* 6 "0d, positive pole only the low-ohmic winding (1) is now traversed by current. In this way is prevented a further seizure of the respective final switch.

By the contacts t and t. the tip wire and the ring wire are connect-ed through to the final switch after the wipers va and '21?) of the pie-selector have been set on to the connecting lines leading to this final switch or connector. The closing of the contacts r and 7' which has already taken place when switching in the relay R, remains first inoperative with the assumed direction of trafiic. They are provided tor the opposite direction of traific (to the subscriber TS) and then serve for connecting the automatic answering or back ring device shown in the upper part of Fig. 3.

During the testing of the pre-selector VlV for the idle or disengaged final switch LlV (Fig. 41) the relay 0 pertaining to it has responded. I

By the contact 0 of the relay C, the cwire, which had previously been passed is switched through the mechanical contact is oi the final switch LlV, directly over to the negative pole thereby enabling the subsequent resetting of the selector. By the contact 0 a circuit is prepared for the testing relay having two coils or windings p 39 while the reversal of the contact enables the subsequent response of the relay U.

On connecting through the two traific wires by closing the contacts t and A (Fig. 3) a circuit was furthermore completed for the transmitting relay ES, viz: centre M of the source of current at the central oflice, relay ES, rc' ance V7,, 21, m o1), b-wire 4), Pg, Hm, HA minus pole. The direction of the current in this circuit is such that the armature as of the transmitting relay ES is reversed from the position of rest shown into the service osition of rest and thus by the reversal of inc d rection of the current in the receiving relay E a free signal is given to the subscriber T This free or disengaged signal may consist of an acoustic or optic signal or may be utilized for starting the apparatus, for instance for connecting the driving motor to the supply.

The resistance W connected in series with the transmitting relay ES may, like the resistance L, be provided for the balancing of the lines.

After receipt of the free signal the sub scriber operates tl e dial in the usual manner and thus controls the transmitting contact- 3 or an equivalent impulse contact so that by stepwise reversal of the direction of the current in the receiving relay ER of the oflice its armature by intermittent motion reversed into the (illustrated) working position. In the working posi'ion of er the relay X is shortcn-cuitcd every time, but (this relay is fitted with time lag niecl risin so that it re mains permanently id in spite of the intermittent short-circuiting; on the other hand the impulse relay A at the iinal switch Ll? (Fig. l) is intermittently energized every t me the armature is changed over into the n or g position, which re my in the position of rest of the armature cr is at both source of current at the cities and is thus not energized positive pole, Uix SS cr, i on, tip wire 9 A, SS Uri negative pole.

By the first series of impulses the lifting nr' et ll of the final switch lfd is controlled in lmown manner by means of he impulse contact (1 of the impulse relay A so that the first" switch is lifted into the desired decade: positive pole, a V, m, co l-l, UAi, negative pole. Durii the first lifting step the mechanical c ct ,l', is opened and 70 closed, but the response of the relay U is prevented for "the time being, as simultaneously with the. first switching on of the lifting magnet H the time lag relay V connected in series with the magnet is excited and the contact c opene l.

in consequence of its time lag the relay V rem constantly energized during the hrst seri' j iin ulses and drops off only after completion of the series of impulses, i. e. when sn s connected to the negative pole of. the

the final switch stands in the desired decade.

By the then closing, contact 41 the following circuit is completed for the relay U: positive pole, mechanical contact 76 '0 0 U (2) (11 2, H, c-wire, UA negative pole. V c

The relay U serves for changing over from lifting to rotatin Owing to the provision of the r versed contact a the following series of impulses will not be conducted to the lifting magnet H but to'the rotary magnet D which brings the iinal switch within the decade reached into the desired contact position.

Up to the arrival of the second seriesof impulses the reversing relay U remains energized in the following ircuit: positive pole, I6 c 0 U (2), c-wire, Ulla negalive pole. As soon as then the impulses of the second series arrive, the rotary magnet is stepwise energized in the following'circuit: positive pole, impulse contacts a V, 10 10 D, UA negative pole. During the first impulse the relay V is also energized which in its turn holds its armature attracted during the entire series of impulses. The excitation of the relay U is then maintained through the winding 1 in the circuit: positive pole, 0 24 ll (1), c-wire, UA negative pole. After the completion of the second series of impulses the circuit for the winding 2 of the relay U is again completed and maintained up to the response of the testing relay P. V

The contact u thus remains permanently open during the second series of impulses (rotating), so that the closings of the contact (Z taking place when the rotary magnet Dis attracted remain inoperative since on the other hand the contact 42 is also open during the series ofimpulses, These contacts become operative only when on completion of the traffic the selector should automatically be turned back into the inoperative position. The shaft contact 10 serves the same purpose, said contact holding the lifting magnet H disconnected up to the final resetting of the selector; by the second shaft contact 10 on the other l1and,ia changing over of the ring wire .is effected, which on making the connect'ion becomes operative when the line selected is busy. After the dropping off of the relay U a busy potential is connected over. the circuit H4, te 79 to the ring circuit for the testing relay P which when the connecting line to be extended is idle or the subscribers apparatus 1s connectedtto the final switch contact, responds along the circuit: c-wire, wiper Z0, 0 M5, 42 P (2), P

(l) c-wire, Ulla negative pole.

The testing relay P now responds and short circuits by means of its contact p the higl1-- ohmic winding (2), whereby a further seizure is prevented in known manner. By the contacts 72 and 32 the tip wire and the ring wire coming from the pro-selector (F i 8), are connected through to the repeating device (Fig. 5), and simultaneously the impulse relay A is disconnected so that further current impulses can pass only to the repeater and the further selectors respectively.

By the contact 10 the energizing circuit for the relay U (2) has furthermore been broken so that finally this relay drops open. By the closing of the contact a a circuit for the resetting or" the final switch is then prepared while the contact it. connects the 0- wire to the positive pole and closes an additional circuit for the already excited testing relay P along the circuit: positive pole, UA SS u 0 39,, P (1), c-wire, UA, negatlve pole.

The subscriber is now able to continue the selection. The impulses pass in the manner described through the tip wire to the contact 39 at the final switch LlV (Fig. 4), but are not, as before, conducted to-the impulse relay A, but to the receiving relay E of the repeater (Fig. 5), the armature of which, on being connected through (by the contact 37 is first turned into the service rest position: positive pole (Fig. 3), UA SS er, t ta, c-wire at), 32 tip wire (Fig. '5) E M. By the contact 6 the impulses are retransmitted to the transmitting relay S of the repeater along the circuit: positive pole, e EK 7L SK S M. The contact 8 which had likewise been turned into the service rest position, in its turn passes the impulses across the wiper la of the final switch LVV (Fig. 4) to the further selectors located in the substation ZA. (Fig. 6) along the circuit: positive pole or negativepole, sz iktip wire (Fig. 4), la, tip wire (Fig. (5),

In the office ZA further selectors are operated by the impulses in usual manner and finally the pie-selector V'W of the desired subscriber TS is engaged by the energization of the relays I and T. Both relays are connected to the c-wire and are made to respond in the following circuit: ZA, 0'-wire, I, '00, T (1), T ml, positive pole.

By the testing relay T the contacts t and t. are closed and thereby the two transmission wires are connected through to the desired subscriber TS.

During the througl'i connection the relay ES is changed over in the ring wire, so that by reversing the armature es the receiving relay E of the subscriber TS also passes into the service rest position in which is ef-- fected the connection of the subscribers apparatus. The transmitting contact S is then also reversed so that in the central otfice the relay ER is reversed and the relay X energized. By the contact 00 the auxiliary relay R is connected in circuit.

In the same circuit with the testing relay T" the relay 1 is also made to respond, which with its contact '5 prepares the response ol the answering device and at the same time prepares a resetting circuit for the said device by opening the contact 2' This device, which is shown at the upper part of Fig. 6, consists of a rotary magnet DN, which switches the wipers (L and d stepwise forward. The forward motion takes place at regular intervals by means of a contact a, which may be connected to the transmitter AN of the answering device. As such transmitters, we may employ apparatus of the type described and illustrated in the pending application of August Jipp and others filed in the United States Patent Ofiice on January 4-, 1930, Serial No. 418,460.

As the relay 1 is attracted and the contact 2' thus permanently turned into the working position the rotary magnet of the answering device DN' receives an impulse every time the contact 2 is closed over the cuit: positive pole, 2, 2' wiper d DN, negative pole.

The wipers d d are thus moved forward stepwise at regular intervals, until the wiper (Z1, runs on to the last contact, across which it first receives no further impulse, as the contact 2' is open.

During the stepwise forward motion of the wipers a definite sequence of impulses cor responding with a signal, is in every position transmitted through the wiper (Z2, into the ring wire. The impulse combinations are produced in the transmitting device AN of the answering device, one signal being apportioned to each of the transmitting lines SL of the said device, which signal together with the others forms a characteristic, for

instance the name of the called subscriber.

Of the transmitting lines SL only five are represented in the example illustrated, but it will be understood that their number may be larger or smaller according to requirements.

The impulse series dispatched b the transn'iitting apparatus AN across the wiper (Z; of the answering device corresponding with the characteristic of the called subscriber pass over the ring wire 6, the selectors of the substation ZA, the ring wire and the final switch LVV (Fig. 4) to the receiving relay E of the transmitting arrangement (Fig. 5). The following circuit is completed: AN (Fig. 6), SL, 6Z ring wire 7), ZA, ring wire (Fig. 4), lb, ring wire (Fig. 5), E M.

The connection illustrated is, as already mentioned, based upon the assumption that impulse sequences correspond with the liveunit code employed in printing telegraphs operating on the start-stop principle.

These five-unit code signals are initiated by a start impulse effecting the release of the receiver shaft and, as a rule, finished by a stop impulse. The start impulses of the signal combination dispatched by the answering device are so directed that they re yerse the connection of the armature 6 of the receiving relay E in the transmission apparatus from the positive to the negative pole. The release magnet EM of the repeater for the direction from the called to the calling subscriber is then made to re spend so that the receiver wiper EB is released and carried along by the revolving shaft of the repeater for one revolution. The speed of rotation of the shaft is adapted to the speed of the telegraphing signals so that a correct storage of the individual impulses occurs.

For storing the individual impulses of the received five-unit code the polarized relays R -R are provided, which are connected on the one hand to the centre M of the source of current at the exchange, on the other hand to the segments 1 to 5 of the receiving contact disk. If during the rotation of the contact arm the receiving wiper BB connects successively the segments 1 to 5 with the contact disk EK and thus also with the armature c of the receiving relay, then every time one of the contact segments connected with the impulse storing relay is swept by the wiper, such relay is reversed towards the positive or the negative pole, according to whether the armature c of the receiving relay E; is in one or the other position. The live-unit code dispatched by the answering device is thus first transmitted to the storing relays.

An adequate time after the starting of the receiving wiper EB the cam N connected with it closes the contact 97 whereby the release magnet EM is excited andnowthetransmitting wiper SM is also released for one revolution. Simul eousl with the release of the transmifiing wiper S13 there is energized the auxiliary relay SH: connected in series with the rein: 1e magnet SEE-3., which may be a neutral relay, and by the temporary reversal of the contact sh the start impulse is transmitted to the transmitting relay S along the circuit: negative pole, 87b SE SK S M.

During its further revolution the transmitting brush SB: connects the contact disk 8K successively with the segments 1 to 5. which in their turn are connected to thearmaturcs of the storing relays R to In this way the impulses stored up by the storing relay are transmitted to the transmitting relay S in accurately correct length and time sequence, the relay turning its contact a, in correspondence with the impulses towards the positive or negative pole.

From here the corrected impulses pass over the pre-selector VW and the t ansmitting relay ES (Fig. 3), to the calling subscriber TS along the circuit: positive or negative pole,-

s 5), ring wire, p 4), ring Wire, '0?) (Fl 8), m 2 ,lV ,llS,M. The contact as of the transmitting relay ES passes the impulses, in the manner described, to the receiving relay E of the subscriber T5, so that this subscriber receives the impulse combinations corresponding with the characteristic of the ca led subscriber and thus receives confirmation that the correct connection has been made.

lt has been assumed that the receiving motor of the subscriber is switched inas soon as the subscriber-receives the free signal of the central ollice, by reversing the armature as into the service position of rest. It is, however, also possible to effect the connection only when the reception of the characteristic or identifying signal of the desired party dispatched by the answering or back signal device begins.- The switching-in could then, for example, take place by the first impulse or by a special combination of impulses which preccde the character atic signal proper.

To enable the interchange of telegrams to be commenced, it is necessary to elin'iinate the bypass of the correcting impulse repeater (Fig. provided for the direction from the calling subscriber to the called subscriber. This is preferably effected by the repeater provided for the opposite direction of traliic on reception of the confirmation by the an swering device, but it will be understood that another switching process occurring after the extension of the connection may, of course, also be utilized for eliminating theby-pass or forstarting the repeater. If the characteristic dispatched by the answering device is employed for initiating the necessary switching process, a special combination of impulses may, for instance, be employed, which renders op ative a receiving appzn'atus responding exclusively to this cinnhination of impulses and thereby brings about the elimination of the bypass. The impulse combination may during the recall be transmitted at any desired period for instance at the beginning or at the end of the return call.

In most cases it will, however, suffice if only some, for instance two, impulses of a combination signal comply with a certain condition. For the repeat arrangement illustrated in Fig. 5 it is, by way of example, assumed that the first and the last impulses of thefive-unit code must have opposite directions of current. On receipt of such a signal the armatures of the storing relays R and R will have opposite positions, so that a circuit for the holding relay H (1) is completed. The holding relay disconnects itself automatically by its contact it, but simultaneously a circuit for the other winding of the holding relay is completed lid through the contact in, viz: positive pole, contact (Fig. of the relay C (Fig. 4), k H (2) negative pole.

The holding relay H thus remains permanently energized until it is on breaking the connection made to drop oil by opening the contact 0 The holding relay will drop only when the armatures of the storing re lays R and R are in the same position. The last of the transmitted signals must thus have a certain property, but this condition can easily be fulfilled, as for the purposes of disconnection or clearing a special ciearing signal is generally transmitted.

During the response of the holding relay H the contacts 72. h; and ]L5 are also reversed whereby the correcting impulse repeater, provided for the direction from the calling to the called subscriber, is made ready for service.

If telegraph signals are now dispatched from the calling subscriber, these pass first, in the manner described above, to the receiving relay E of the repeater apparatus, but they are not, as before, transmitted directly from the armature e of this relay to the transmitting relay S but pass, as 71. is open and 7a., is closed, to the release magnet EH of the receiving wiper EB along the circuit: negative pole, 0 Eli, Eli, h EM positive pole. it is to be noted that the service position of rest of the armature c, is not at once identical with the position of rest illustrated, and that, as described above, the armature 6 is reversed into the service position of rest only during the making of the connection.

After the release of the receiving wiper EB, by the start impulse the individual impulses corresponding with the live-unit code are passed to the storing relays R te B in the manner already described for the other repeater, by being connected in succession to the contact disk EK through the contact segments 1 to 5.

The release of the transmitting wiper SB takes place a short time after the start of the reciving brush FB as soon as the release magnet SM is energized through the cam contact a Sin'lultaneously the start 1mpulse to the transmitting relay S: is transmitted by the auxiliary relay SH through the closed contact h of the holding relay H along the circuit: negative pole, sh 7L5, contact segment 0, S13 SE S hi. The transmission of the remaining signal nnpulses takes place when the transmitting wiper SB sweeps over the segments 1 to The corrected impulses pass from here over the tip wire and the final switch Ll (Fig. 4:) to the substation ZA (Big. 6) and hence to the desired subscriber T The circuit is as follows: positive or negative pole, 8 (Fig. 5), tip wire, Z0 (Fig. P, tip wire, ZA (Fig. 6), tip Wire a, 6' lV ES, M.

The armature es of the transmitting relay ES then controls the receiving magnet E at the subscribers station ES.

The'impulses to be transmitted from the called subscriber TS to the calling subscriber TS take the'following path: The transmitting contacts controls the receiving relay ER at the oilice of the called subscriber TS. impulses through the contact t of the testing relay T, the contact 1 of the auxiliary relay R, the wiper d of the answering device and the ring wire Z) to the substation Zi-i. After the completion of the answering signal, this connecting line is connected through by the wiper d of the answering device as soon as the wiper has reached the last contact. In this position the exciter circuit for the rotary magnet DN of the answering device is interrupted when the wiper 6Z runs on to the last contact as already described.

From the substation ZA the impulses pass through the ring wire to the wiper lb of the al switch LlV (Fig. 4) and from here over the tip wire to the receiving magnet E of the repeating apparatus (Fig. 5). The further transmission of the telegraph signals occurs in exactly the same manner as described above for the transmission of the confirmation by the answering device.

The release of the connection can take place from either one or the other of the two subscribers. If, for instance, the calling subscriber TS turns the transmitting contact 8 from the service position of rest back into tne position shown (false position of rest), the contact er of the receiving relay ER at the central office is likewise constantly turned back into the position of rest shown. The relay X is thus short circuited so that it releases with time lag and also causes the relay R to release by opening its contact an. Before the slow release of the relay R takes place and its contact 13 opens, a circuit for the transmitting relay ES is completed by the reciosing of the contact 02 which moves the armature of this relay back into the position of rest shown, viz positive pole, UA SS resistance Vi r m, h, resistance W ES, M.

By reversing the contact es the direction of the current in the receiving magnet E of the subscriber TS is likewise reversed. This procedure may preferably be utilized for disconnecting the transmitting and receiving gear or the driving motor at the subscribers station. The auxiliary circuit for the relay BS is interrupted as soon as the relay R has released and the contact is opened.

The contact m interrupts the circuit for the winding (1) of the testing relay T so that the relay releases.- The contact t then closes the restoring circuit for the pre-selec- The contact 61' transmits the tor VXV, which is thereby moved into the initial position: positive pole, 'vrl continuoussegment, t rotary magnet DV, SS. relay interrupter RU, UA negative pole. The pre-selector is arrested as soon as it has attained its original position in which the exciter circuit for the rotary magnet is interrupted. By the contacts t and t, of the testing relay the through connection of the two traflic wires had been eliminated, so that during the rotation of the pre-selector any breakdown of the switchgear connected; with the pre-selector contacts is effectively avoided.

Simultaneously with the testing relay T of the pre-selector VW 3) the relay C at the final switch L'W a) has released. the contact 0 the restoring of'the final switch is then prepared while the contact 0 releases testing relay P of the final switch. The contacts 32 and 9 disconnect the tratfic wires a and 5 leading to the repeater device, while simultaneously the new connection is prepared by switching on the impulse relay A.

The contact 293 of the testing relay P closes an eXciter circuit for the rotary magnet D oi the final switch, the wipers being thereby rendered operative: negative pole, UA D, [1 a 0 o positive pole. When the rotary magnet attracts, it closes its contact (Z- which causes the relay U to respond in the circuitzpositive pole, 70 '0 (Z, U c-wire, UA... negative pole. The relay U pulls up and opens the contact 24 whereby the exciter circuit of the rotary magnet D is interrupted and its armature drops ofi' again. This breaks the contact d so that the relay U releases again. By closing the con tact 14 the rotary magnet D is switched in againand the relay U is energized again.

This alternate switching on and off in the manner of relay interrupter continues until the final switch has in the course of its rotary motion attained the last position in which it automatically drops back into the initial position. During this dropping back the mechanical ontacts 70 and 7c: are reversed, a fresh exciter circuit for the relay C being prepared by 70 and the automatic interrupter circuit of the rotary magnet being interrupted by During the resetting of the final switch the shaft contact '10, is also reversed in the end position, and connects the ring wire 7) again to the negative pole and thus eliminates the seizure of the final switch. The contact 10 prepares the circuit for the lifting magnet H which should become operative when the next connection is made. By disconnecting the c-wire, resetting of the engaged selectors in the substation ZA 6) is caused.

By the release of the relay 0 at the final switch LVJ (Fig. 4c) the contact 0 which forms part of the repeating apparatus (F ig. 5) is broken again so that the holding relay H releases and by the resetting of the contacts h in and Its into the position shown'causes the by-pass-ing for one of the two repeaters.

After the resetting of the selectors in the substation .ZA (Fig. 6), the c-wire leading to the pro-selector VW of the called subscriber is interrupted so that the relays I and T release. The contact 2' then connects up for the answering device, which is in the last position arelay interrupter UN which moves the wipers of said device into the initial position, in the circuit: negative pole, DNQd 2' UN, positive pole. contact 111" is provided only for the case that the subscribershould bring about the release of the selectors already during the giving of the answering signal. The forward motion of the answering device into the position of rest is then effected through the wiper al and the continuous segment, in the circuit: negative pole, DN, d u UN, positive pole.

During the release of the testing relay T the contacts 15 and ti were broken and thereby the trafiic wires a and Z2 interrupted. Prior to this the direction of the current in the transmittingrelay ES was already reversed during the changing-over of the transmittingcontact s at the calling subscriber TS to the normal path used for transmitting the telegraph signals, and thus the armature es of this relay was permanently turned back into the position of rest shown. In this way the receiving relayE at the subscribers' station TS is reversed whereby the subscribers apparatus is switched off andthe transmitting contact s is positively moved from the service position of rest into the position of rest shown. This reversing of the relay ER at the central oiiice then causes the resetting of the contact er" and the release of the relay X in the manner. described above. The relay X disconnects in its turn with its contact 001 the auxiliary relay R which opens with a slow action.

The whole plant is now again in the inoperative state.

We claim as our invention:

1. In a telegraph system comprising a plurality of line sections and regenerative telegraph repeaters interposed between contiguous line sections for transmittingtelegraphic signal currents, electrically controlled means for disconnecting and by-passing said telegraph repeaters.

2. In a telegraph system comprising a plurality of line sections and regenerative telegraph repeaters interposed between contiguous line sections for transmitting telegraphic signal currents, electrically controlled means for disconnecting and bypassing said telegraph repeaters, the oontrol of said means being etiected by the initiation and the termination of the telegraphic communication.

The rest for the transmission of telegraphic signal currents; means for switching said repeaters into connectlons established between sald subscribers stations, relays controlling the lastmentioned means, and means for actuating said relays by the establishing of said connections. I Y

4-. In a telegraph exchange system comprising a plurality of subscribers stations, one or more central ofiices, switch means at said central ofiice or offices for establishing connections between said subscribers stations, and regenerative telegraph repeaters for the transmission of telegraphic signal currents; means by which a special impulse combination is sent back on extending the connection to the called subscribers station, and means for switching said telegraph repeaters into connections established between said subscribers stations, said last-mentioned switching means being controlled by said special impulse combination.

5. In a telegraph exchange system compris- 4 mg a plurality of subscribers stations, one

or more central offices, switch means at said central oflice or ofiices for establishing conne'ctions between said subscribers stations, and regenerative telegraph repeaters for the transmission of telegraphic signal currents; means for producing predetermined impulse combinations, and means for switching said telegraph repeaters into connections established between said subscribers stations, said last-mentioned switching means being controlled by only a portion of the individual impulses constituting an impulse combination.

6. In a telegraph exchange system comprising a plurality of subscribers stations, one or more central ofiices, switch means at said central ofhce or oflices for establishing connections between said subscribers stations, and regenerative telegraph repeaters for the transmission of telegraphic signal currents; means for switching said telegraph repeaters into connections established between said; subscribers stations, and an answering or back signal device controlling the last-mentioned switching means, said device being arranged to send to the calling subscribers I station, if the called subscribers station is disengaged, a characteristic identifying the latter station.

7. In a telegraph exchange system comprising a plurality of subscribers stations, one 80 or more central oflices, switch means at said central ofiice or offices for establishing connections between said subscribers stations, and regenerative telegraph repeaters for the transmission of telegraphic signal currents; means for switching said telegraph repeaters into connections established between said subscribers stations, an answering or back signal device controlling the last-mentioned switching means, a relay for actuating said device, and means for causing said relay to respond when the desired connection has been established. 

